flingman1 wrote:Do not want EFM furnace to handle the hot water - never enough , has to run all summer burning oil as well as winter -- want to use furnace/boiler for heat only in winter & install stand alone high efficient water heater
Okay, so this is NOT a Coal Unit...strictly oil...and you want to have plenty of DHW all seasons.
Did it ever make enough hot water?
Might be the internal coil has become scaled up inside and reducing its output capacity.
A good coil cleaning or outright coil replacement could get you back in business.
The idea to add an electric water heater to not burn oil in summer make sense.
Perhaps you would want to pre-heat the water into the electric water heater in the winter through the boiler.
flingman1 wrote:I want to install a stand alone water heater - how to disconnect furnace from starting for hot water (only need for heat in winter )
Remove electric power by turning off switch or circuit breaker.